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Blazquez S, Abascal JLF, Lagerweij J, Habibi P, Dey P, Vlugt TJH, Moultos OA, Vega C. Computation of Electrical Conductivities of Aqueous Electrolyte Solutions: Two Surfaces, One Property. J Chem Theory Comput 2023; 19:5380-5393. [PMID: 37506381 PMCID: PMC10448725 DOI: 10.1021/acs.jctc.3c00562] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Indexed: 07/30/2023]
Abstract
In this work, we computed electrical conductivities under ambient conditions of aqueous NaCl and KCl solutions by using the Einstein-Helfand equation. Common force fields (charge q = ±1 e) do not reproduce the experimental values of electrical conductivities, viscosities, and diffusion coefficients. Recently, we proposed the idea of using different charges to describe the potential energy surface (PES) and the dipole moment surface (DMS). In this work, we implement this concept. The equilibrium trajectories required to evaluate electrical conductivities (within linear response theory) were obtained by using scaled charges (with the value q = ±0.75 e) to describe the PES. The potential parameters were those of the Madrid-Transport force field, which accurately describe viscosities and diffusion coefficients of these ionic solutions. However, integer charges were used to compute the conductivities (thus describing the DMS). The basic idea is that although the scaled charge describes the ion-water interaction better, the integer charge reflects the value of the charge that is transported due to the electric field. The agreement obtained with experiments is excellent, as for the first time electrical conductivities (and the other transport properties) of NaCl and KCl electrolyte solutions are described with high accuracy for the whole concentration range up to their solubility limit. Finally, we propose an easy way to obtain a rough estimate of the actual electrical conductivity of the potential model under consideration using the approximate Nernst-Einstein equation, which neglects correlations between different ions.
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Affiliation(s)
- Samuel Blazquez
- Dpto.
Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Jose L. F. Abascal
- Dpto.
Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
| | - Jelle Lagerweij
- Engineering
Thermodynamics, Process and Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands
| | - Parsa Habibi
- Engineering
Thermodynamics, Process and Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands
- Department
of Materials Science and Engineering, Faculty of Mechanical, Maritime
and Materials Engineering, Delft University
of Technology, Mekelweg
2, 2628CD Delft, The Netherlands
| | - Poulumi Dey
- Department
of Materials Science and Engineering, Faculty of Mechanical, Maritime
and Materials Engineering, Delft University
of Technology, Mekelweg
2, 2628CD Delft, The Netherlands
| | - Thijs J. H. Vlugt
- Engineering
Thermodynamics, Process and Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands
| | - Othonas A. Moultos
- Engineering
Thermodynamics, Process and Energy Department, Faculty of Mechanical,
Maritime and Materials Engineering, Delft
University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands
| | - Carlos Vega
- Dpto.
Química Física I, Fac. Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain
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2
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Perin L, Gallo P. Phase Diagram of Aqueous Solutions of LiCl: a Study of Concentration Effects on the Anomalies of Water. J Phys Chem B 2023; 127:4613-4622. [PMID: 37167579 DOI: 10.1021/acs.jpcb.3c00703] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We perform molecular dynamics simulations in order to study thermodynamics and the structure of supercooled aqueous solutions of lithium chloride (LiCl) at concentrations c = 0.678 and 2.034 mol/kg. We model the solvent using the TIP4P/2005 potential and the ions using the Madrid-2019 force field, a force field particularly suited for studying this solution. We find that, for c = 0.678 mol/kg, the behavior of the equation of state, studied in the P-T plane, indicates the presence of a liquid-liquid phase transition, similar to what was previously found for bulk water. We estimate the position of the liquid-liquid critical point to be at Tc ≈ 174 K, Pc ≈ 1775 bar, and ρc ≈ 1.065 g/cm3. When the concentration is tripled to c = 2.034 mol/kg, no critical point is observed, indicating its possible disappearance at this concentration. We also study the water-water and water-ions structure in the two solutions, and we find that at the concentrations examined the effect of ions on the water-water structure is not strong, and all the features found in bulk water are preserved. We also calculate the hydration number of the Li and Cl ions, and in line with experiments, we find the value of 4 for Li+ and between 5.5 and 6 for Cl-, confirming the good performances of the Madrid-2019 force field.
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Affiliation(s)
- Leonardo Perin
- Dipartimento di Fisica, Università Roma Tre, Via della Vasca Navale 84, I-00146 Roma, Italy
| | - Paola Gallo
- Dipartimento di Fisica, Università Roma Tre, Via della Vasca Navale 84, I-00146 Roma, Italy
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3
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Yao N, Chen X, Fu ZH, Zhang Q. Applying Classical, Ab Initio, and Machine-Learning Molecular Dynamics Simulations to the Liquid Electrolyte for Rechargeable Batteries. Chem Rev 2022; 122:10970-11021. [PMID: 35576674 DOI: 10.1021/acs.chemrev.1c00904] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Rechargeable batteries have become indispensable implements in our daily life and are considered a promising technology to construct sustainable energy systems in the future. The liquid electrolyte is one of the most important parts of a battery and is extremely critical in stabilizing the electrode-electrolyte interfaces and constructing safe and long-life-span batteries. Tremendous efforts have been devoted to developing new electrolyte solvents, salts, additives, and recipes, where molecular dynamics (MD) simulations play an increasingly important role in exploring electrolyte structures, physicochemical properties such as ionic conductivity, and interfacial reaction mechanisms. This review affords an overview of applying MD simulations in the study of liquid electrolytes for rechargeable batteries. First, the fundamentals and recent theoretical progress in three-class MD simulations are summarized, including classical, ab initio, and machine-learning MD simulations (section 2). Next, the application of MD simulations to the exploration of liquid electrolytes, including probing bulk and interfacial structures (section 3), deriving macroscopic properties such as ionic conductivity and dielectric constant of electrolytes (section 4), and revealing the electrode-electrolyte interfacial reaction mechanisms (section 5), are sequentially presented. Finally, a general conclusion and an insightful perspective on current challenges and future directions in applying MD simulations to liquid electrolytes are provided. Machine-learning technologies are highlighted to figure out these challenging issues facing MD simulations and electrolyte research and promote the rational design of advanced electrolytes for next-generation rechargeable batteries.
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Affiliation(s)
- Nan Yao
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Xiang Chen
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Zhong-Heng Fu
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
| | - Qiang Zhang
- Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing 100084, China
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Prasad S, Gupta M. Solvation of gold nanoparticles passivated with functionalized alkylthiols: A molecular dynamics study. J Mol Liq 2022. [DOI: 10.1016/j.molliq.2021.118342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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5
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Demmel F. Structural relaxation in the aqueous solution LiCl ⋅ 6D2O by quasielastic neutron scattering. J Mol Liq 2021. [DOI: 10.1016/j.molliq.2021.115915] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Wang M, Liu S, Ji H, Yang T, Qian T, Yan C. Salting-out effect promoting highly efficient ambient ammonia synthesis. Nat Commun 2021; 12:3198. [PMID: 34045462 PMCID: PMC8160333 DOI: 10.1038/s41467-021-23360-0] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 04/18/2021] [Indexed: 02/04/2023] Open
Abstract
The electroreduction of nitrogen to ammonia offers a promising alternative to the energy-intensive Haber-Bosch process. Unfortunately, the reaction suffers from low activity and selectivity, owing to competing hydrogen evolution and the poor accessibility of nitrogen to the electrocatalyst. Here, we report that deliberately triggering a salting-out effect in a highly concentrated electrolyte can simultaneously tackle the above challenges and achieve highly efficient ammonia synthesis. The solute ions exhibit strong affinity for the surrounding H2O molecules, forming a hydration shell and limiting their efficacy as both proton sources and solvents. This not only effectively suppresses hydrogen evolution but also ensures considerable nitrogen flux at the reaction interface via heterogeneous nucleation of the precipitate, thus facilitating the subsequent reduction process in terms of both selectivity and activity. As expected, even when assembled with a metal-free electrocatalyst, a high Faradaic efficiency of 71 ± 1.9% is achieved with this proof-of-concept system.
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Affiliation(s)
- Mengfan Wang
- grid.263761.70000 0001 0198 0694College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, China
| | - Sisi Liu
- grid.263761.70000 0001 0198 0694College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, China
| | - Haoqing Ji
- grid.263761.70000 0001 0198 0694College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, China
| | - Tingzhou Yang
- grid.263761.70000 0001 0198 0694College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, China
| | - Tao Qian
- grid.263761.70000 0001 0198 0694College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, China ,grid.260483.b0000 0000 9530 8833School of Chemistry and Chemical Engineering, Nantong University, Nantong, China
| | - Chenglin Yan
- grid.263761.70000 0001 0198 0694College of Energy, Key Laboratory of Advanced Carbon Materials and Wearable Energy Technologies of Jiangsu Province, Soochow University, Suzhou, China
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Hoffmann MM, Too MD, Vogel M, Gutmann T, Buntkowsky G. Breakdown of the Stokes-Einstein Equation for Solutions of Water in Oil Reverse Micelles. J Phys Chem B 2020; 124:9115-9125. [PMID: 32924487 DOI: 10.1021/acs.jpcb.0c06124] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
An experimental study is presented for the reverse micellar system of 15% by mass polydisperse hexaethylene glycol monodecylether (C10E6) in cyclohexane with varying amounts of added water up to 4% by mass. Measurements of viscosity and self-diffusion coefficients were taken as a function of temperature between 10 and 45 °C at varying sample water loads but fixed C10E6/cyclohexane composition. The results were used to inspect the validity of the Stokes-Einstein equation for this system. Unreasonably small reverse average micelle radii and aggregation numbers were obtained with the Stokes-Einstein equation, but reasonable values for these quantities were obtained using the ratio of surfactant-to-cyclohexane self-diffusion coefficients. While bulk viscosity increased with increasing water load, a concurrent expected decrease of self-diffusion coefficient was only observed for the surfactant and water but not for cyclohexane, which showed independence of water load. Moreover, a spread of self-diffusion coefficients was observed for the protons associated with the ethylene oxide repeat unit in samples with polydisperse C10E6 but not in a sample with monodisperse C10E6. These findings were interpreted by the presence of reverse micelle to reverse micelle hopping motions that with higher water load become increasingly selective toward C10E6 molecules with short ethylene oxide repeat units, while those with long ethylene oxide repeat units remain trapped within the reverse micelle because of the increased hydrogen bonding interactions with the water inside the growing core of the reverse micelle. Despite the observed breakdown of the Stokes-Einstein equation, the temperature dependence of the viscosities and self-diffusion coefficients was found to follow Arrhenius behavior over the investigated range of temperatures.
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Affiliation(s)
- Markus M Hoffmann
- Department of Chemistry and Biochemistry, State University of New York College at Brockport, Brockport, New York 14420, United States
| | - Matthew D Too
- Department of Chemistry and Biochemistry, State University of New York College at Brockport, Brockport, New York 14420, United States
| | - Michael Vogel
- Institute of Condensed Matter Physics, Technical University Darmstadt, Hochschulstraße 6, Darmstadt 64289, Germany
| | - Torsten Gutmann
- Institute of Physical Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 8, Darmstadt D-64287, Germany
| | - Gerd Buntkowsky
- Institute of Physical Chemistry, Technical University Darmstadt, Alarich-Weiss-Straße 8, Darmstadt D-64287, Germany
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Iamprasertkun P, Ejigu A, Dryfe RAW. Understanding the electrochemistry of "water-in-salt" electrolytes: basal plane highly ordered pyrolytic graphite as a model system. Chem Sci 2020; 11:6978-6989. [PMID: 34122994 PMCID: PMC8159404 DOI: 10.1039/d0sc01754j] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 06/05/2020] [Indexed: 12/21/2022] Open
Abstract
A new approach to expand the accessible voltage window of electrochemical energy storage systems, based on so-called "water-in-salt" electrolytes, has been expounded recently. Although studies of transport in concentrated electrolytes date back over several decades, the recent demonstration that concentrated aqueous electrolyte systems can be used in the lithium ion battery context has rekindled interest in the electrochemical properties of highly concentrated aqueous electrolytes. The original aqueous lithium ion battery conception was based on the use of concentrated solutions of lithium bis(trifluoromethanesulfonyl)imide, although these electrolytes still possess some drawbacks including cost, toxicity, and safety. In this work we describe the electrochemical behavior of a simple 1 : 1 electrolyte based on highly concentrated aqueous solutions of potassium fluoride (KF). Highly ordered pyrolytic graphite (HOPG) is used as well-defined model carbon to study the electrochemical properties of the electrolyte, as well as its basal plane capacitance, from a microscopic perspective: the KF electrolyte exhibits an unusually wide potential window (up to 2.6 V). The faradaic response on HOPG is also reported using K3Fe(CN)6 as a model redox probe: the highly concentrated electrolyte provides good electrochemical reversibility and protects the HOPG surface from adsorption of contaminants. Moreover, this electrolyte was applied to symmetrical supercapacitors (using graphene and activated carbon as active materials) in order to quantify its performance in energy storage applications. It is found that the activated carbon and graphene supercapacitors demonstrate high gravimetric capacitance (221 F g-1 for activated carbon, and 56 F g-1 for graphene), a stable working voltage window of 2.0 V, which is significantly higher than the usual range of water-based capacitors, and excellent stability over 10 000 cycles. These results provide fundamental insight into the wider applicability of highly concentrated electrolytes, which should enable their application in future of energy storage technologies.
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Affiliation(s)
- Pawin Iamprasertkun
- Department of Chemistry, University of Manchester Oxford Road Manchester M13 9PL UK +44 (0)161-275-4598
- National Graphene Institute, University of Manchester Oxford Road M13 9PL UK
| | - Andinet Ejigu
- Department of Chemistry, University of Manchester Oxford Road Manchester M13 9PL UK +44 (0)161-275-4598
- National Graphene Institute, University of Manchester Oxford Road M13 9PL UK
| | - Robert A W Dryfe
- Department of Chemistry, University of Manchester Oxford Road Manchester M13 9PL UK +44 (0)161-275-4598
- National Graphene Institute, University of Manchester Oxford Road M13 9PL UK
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Wang J, Lin H, Li F, Li S, An S, Yuan J. Concentration-dependent structure of mixed NH4Cl and (NH4)2SO4 aqueous solutions from the X-ray diffraction, Raman spectroscopy and molecular dynamics simulations. J Mol Struct 2019. [DOI: 10.1016/j.molstruc.2019.01.082] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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11
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A comparison of classical interatomic potentials applied to highly concentrated aqueous lithium chloride solutions. J Mol Liq 2017. [DOI: 10.1016/j.molliq.2017.07.076] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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12
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Prasad S, Chakravarty C. Solvation of LiCl in model liquids with high to low hydrogen bond strengths. J Chem Phys 2017. [DOI: 10.1063/1.4982828] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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